There are a variety of procedures that require the mixing of two or more substances before the mixed compound can be used. Often, the materials that are mixed are volatile, short lived, vulnerable, expensive, precious, unique or irreplaceable.
There are circumstances in which it is desirable to dispense liquid or semi-liquid materials in a predetermined ratio. The materials may include reactive, two component adhesives, sealants, coating, or potting compounds, in which one material may comprise a resin compound and the other material a catalyst.
Dispensers for two or more components are disclosed in U.S. Pat. Nos. 3,223,083; 2,112,160; 5,290,259; 4,609,371; 4,631,055; 4,735,616; 4,874,368 4,978,336; 4,979,942; 5,104,375; 5,116,315; 5,185,001; 5,290,259; 5,322,510; 5,368,563; 5,376,079; 5,464,396; 5,474,540; 5,520,658; 5,582,596; 5,584,815; 5,605,255; 5,643,206; 5,665,067; 5,887,755; 5,975,367; 5,989,215; 6,234,994; 6,394,982; 5,368,563; 6,454,739 and 6,132,396.
One dispensing application relates to fibrin. Clotting of blood in vivo takes place by conversion of the soluble plasma protein fibrinogen into fibrin, which spontaneously polymerizes into an insoluble gel matrix that can attach to adjacent tissue. The gel matrix stops bleeding and stabilizes structures. Thrombin catalyzed conversion of fibrinogen to fibrin can be reproduced in vitro and has great utility for adhering tissues and achieving hemostasis. Such fibrin sealants and fibrin glues are available commercially and are also made in blood processing laboratories. Preparation and use of fibrinogen-based sealants have been extensively reviewed.
Fibrin sealants and fibrin glues and adhesives based on combining fibrinogen-containing solutions with thrombin-containing solutions are used to reduce bleeding and restore hemostasis during surgical procedures. They have been known and in use for many years during which fibrin technology has evolved significantly. For example, fibrin clots can be made using different concentrations of fibrinogen in conjunction with the thrombin solution. Subsequent developments in fibrin technology include cryoprecipitate fibrinogen. In some applications, concentrated plasma is used as the fibrinogen component in fibrin sealants.
Similarly, various types of applicators for fibrin glue are known. The chemical and biological properties of liquid resulting from combining fibrinogen and thrombin solutions are sometimes difficult to predict. Because of the rapid polymerization upon intimate interaction of fibrinogen and thrombin, it is desirable to keep these two blood proteins separate until application to the site of use. In practice, the two components are typically dispensed simultaneously from separate syringes and brought together by means of an applicator manifold.
With some known assemblies, a retaining means is used to maintain syringes carrying the dispensing materials. One retaining means includes a generally trough-shaped or sleeve-shaped retaining structure including appropriate troughs or sleeves for receiving the syringe bodies. In addition, the retaining means is provided with finger grips laterally projecting in opposite directions. The retaining structure can include elastically yielding snap-in projections that hold the syringe bodies. To actuate the pistons of the syringe bodies, a grip element is used. In particular, the grip element is connected to the pistons of the syringes for stabilizing and improving the guidance of the piston rods when actuating the syringe device. It has also been proposed to connect a guide rod with the common grip element. In order to improve tracking, the guide rod extends through a guide bore formed in the retaining means.
Methods for making platelet gels from blood or blood components are also well known. Platelet gels, devices suitable for manufacturing gels from blood components, and methods for making such gels are disclosed in U.S. Pat. Nos. 5,851,169; 6,444,228; 6,475,175; 6,589,153; 6,612,975; 6,596,180; 6,719,901; and 6,793,828 and U.S. Pat. App. Pub. Nos. 2004-0055937 and 2003-0232712. The entire contents of each of these patents and applications are incorporated herein by reference.
Dispensers suitable for applying a gel-like substance (e.g. a platelet gel) to a body are disclosed in U.S. Pat. App. Pub. Nos. 2002-0004038 A1 and 2003-0233067 A1.
Improvements in sprayer type applicator tips remain to be realized. For example, sprayer type applicator tips where a volumetric ratio of the two separate fluids to be dispensed is from 3:1 to 10:1 can encounter significant difficulties. In particular, in some spray applicator systems currently available, the larger volume fluid tends to atomize with ease while the lesser volume fluid will only drip or marginally atomize from respective spray nozzles. This problem can become even more significant when it is desired to have the two components mix as they are applied to a treatment site. Where there is a base media (e.g., platelet rich plasma) and an activator (e.g., thrombin) that can mix and create a fluid that can solidify or gel in as little as 2 seconds, prior art commercialized devices can encounter problems with clogging, providing optimal mixing, and achieving a desired spray pattern.
Additionally, some prior art bead type applicators use a form of hypodermic stainless steel needles to create the two lumens. Although this is effective, one significant shortcoming is that these are considered sharps and require great care in the handling, use, and disposal.
Yet another problem encountered in some prior art assemblies resides in retaining structure designs. Such retaining structures are used to hold the syringe barrels in a parallel state, but fail to hold an associated applicator tip attachment. This may lead to undesired leakage or separation of the syringe barrels and the applicator tip due to assembly errors or the forces encountered during use.